sema: add peer type resolution for vectors

This is consistent with how coercion for vectors work. So now you can do
this:

```
var a: @Vector(2, u16) = .{1, 2};
var b: @Vector(2, u8) = .{2, 1};
const c = @min(a, b);
```

where previously you had to cast explicitly:

```
var a: @Vector(2, u16) = .{1, 2};
var b: @Vector(2, u8) = .{2, 1};
var c: @Vector(2, u16) = b;
const c = @min(a, c);
```

1 files changed, 25 insertions, 0 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index 8c6e3cf05c..a33c9bee6d 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -29875,6 +29875,31 @@ fn resolvePeerTypes(
                 continue;
             },
             .Vector => switch (chosen_ty_tag) {
+                .Vector => {
+                    const chosen_len = chosen_ty.vectorLen();
+                    const candidate_len = candidate_ty.vectorLen();
+                    if (chosen_len != candidate_len)
+                        continue;
+
+                    const chosen_child_ty = chosen_ty.childType();
+                    const candidate_child_ty = candidate_ty.childType();
+                    if (chosen_child_ty.zigTypeTag() == .Int and candidate_child_ty.zigTypeTag() == .Int) {
+                        const chosen_info = chosen_child_ty.intInfo(target);
+                        const candidate_info = candidate_child_ty.intInfo(target);
+                        if (chosen_info.bits < candidate_info.bits) {
+                            chosen = candidate;
+                            chosen_i = candidate_i + 1;
+                        }
+                        continue;
+                    }
+                    if (chosen_child_ty.zigTypeTag() == .Float and candidate_child_ty.zigTypeTag() == .Float) {
+                        if (chosen_ty.floatBits(target) < candidate_ty.floatBits(target)) {
+                            chosen = candidate;
+                            chosen_i = candidate_i + 1;
+                        }
+                        continue;
+                    }
+                },
                 .Array => {
                     chosen = candidate;
                     chosen_i = candidate_i + 1;